1. Field of the Invention
The present disclosure generally relates to methods of controlling thermally activated active material actuators, and more particularly, to a method of controlling heat transfer within the actuator utilizing external elements.
2. Discussion of Prior Art
Thermally activated active material actuators, such as shape memory alloy (SMA) actuators in the Martensitic state, are activated by heating the material to a temperature that is above a prescribed value. With respect to SMA, this causes the material to undergo phase transformation from a Martensitic to an Austenitic state, wherein it contracts and in the process is used to do work. SMA wires, for example, are resistively heated by applying an electrical current there through. Once activated, the actuator must undergo a cooling period prior to being re-actuated. Concerns with this approach include limiting the actuation period, so as to provide more instantaneous actuation, and, limiting the cooling period, which further aids in preventing overheating. Moreover, it is appreciated that extended actuation and cooling periods can cause reduced system response bandwidth, whereas overheating can cause damage to the actuator. It is therefore desirable to have an effective means of accelerating actuation and cooling, so as to streamline actuation and prevent overheating over the life of the actuator.